So I went to the pub to talk to Mike and it turns out he did the right thing and inspected her crotch. Turns out there are no balls and he fingered her pussy to make sure. Or that's what he says. He also spanked her butt with his dick. This is probably for the good. I still don't understand why a girl would walk into a bar and say that she has balls but whatever, and it all made a lot of sense actually. Maybe they had fun with her balls and then decided to keep it a secret and refute all previous drunken claims.
In the morning he was sent to buy some ham and she made him an omelette. He spent the rest of the day drinking as usual. When I met him in the pub he was falling from the chair and throwing stuff around so everything's back to normal.